日本放射線技術学会雑誌
Online ISSN : 1881-4883
Print ISSN : 0369-4305
ISSN-L : 0369-4305
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70 巻, 6 号
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原著
  • 体表指標を用いた肩関節True Anterior-Posterior 撮影の検討
    森田 峻輔, 藤澤 宏信, 加藤 京一, 西中 直也, 筒井 廣明, 中澤 靖夫
    2014 年 70 巻 6 号 p. 519-525
    発行日: 2014年
    公開日: 2014/06/20
    DOIhttps://doi.org/10.6009/jjrt.2014_JSRT_70.6.519
    ジャーナル フリー
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    Radiographic examination of the anterior part of the shoulder includes routine anterior-posterior imaging that enables easy visualization of traumatic injuries and true anterior-posterior imaging that enables the visualization of intra-articular injuries. The X-ray incident angle of true anterior-posterior imaging is affected by physique and posture. However, in many reports, the angle is uniformly determined on the basis of the antero-posterior axis and the horizontal plane. We previously reported that the glenohumeral joint can be visualized with good reproducibility by establishing a reference line on the basis of three points on the body as indicators, namely the posterior view of the under-surface of the acromion, the coracoid process, and the inferior angle of the scapula. However, visualizing the undersurface of the acromion using physical indicators to set the angle for imaging remains problematic. In previous reports, the angle was consistently set at 20° to the horizontal plane, regardless of physique or posture, which resulted in poor reproducibility. After examining the imaging techniques described in previous reports, we describe here an imaging technique using a reference line based on indicators on the surface of the scapula that enables the glenohumeral joint and the undersurface of the acromion to be visualized with good reproducibility.
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  • 位置特徴量の導入と特徴量選択による頸動脈石灰化の自動検出法の改良
    髙橋 龍, 村松 千左子, 原 武史, 林 達郎, 勝又 明敏, 周 向栄, 藤田 広志
    2014 年 70 巻 6 号 p. 526-533
    発行日: 2014年
    公開日: 2014/06/20
    DOIhttps://doi.org/10.6009/jjrt.2014_JSRT_70.6.526
    ジャーナル フリー
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    The purpose of this study was to improve an automated scheme for detecting carotid artery calcification (CAC) in dental panoramic radiographs (DPRs). Using 100 DPRs, the sensitivity of CAC detection employing our previous method was 90.0% with 5.0 false positives (FPs) per image. This study describes two enhancements. One is the adoption of a new feature for the position of CACs in addition to previous features. The other is feature selection employing the support vector machine using all combinations. Five of 12 features were selected. Using our proposed method, the average sensitivity for the same database proved to be 90.0%, with only 2.5 FPs per image. These results indicate the potential effectiveness of the new positional feature and feature selection.
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臨床技術
  • チタン製の脳動脈瘤クリップによる1.5 Tesla- と3 Tesla-MR 画像の歪みとアーチファクトの検討─コバルト60定位手術的照射治療計画に及ぼす影響─
    中澤 寿人, 山室 修, 内山 幸男, 小森 雅孝
    2014 年 70 巻 6 号 p. 534-541
    発行日: 2014年
    公開日: 2014/06/20
    DOIhttps://doi.org/10.6009/jjrt.2014_JSRT_70.6.534
    ジャーナル フリー
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    In gamma knife stereotactic radiosurgery (GKSRS) treatment planning, 1.5 tesla (T)-magnetic resonance imaging (MRI) is normally used to identify the target lesion. Image artifacts and distortion arise in MRI if a titanium clip is surgically implanted in the brain to treat cerebral aneurysm. 3-T MRI scanners, which are increasingly being adopted, provide imaging of anatomic structures with better clinical usefulness than 1.5-T MRI machines. We investigated signal defects and image distortions both close to and more distant from the titanium clip in 1.5-T and 3-T MRI. Two kinds of phantoms were scanned using 1.5-T and 3-T MRI. Acquisitions with and without the clip were performed under the same scan parameters. No difference was observed between 1.5 T and 3 T in local decrease of signal intensity; however, image distortion was observed at 20 mm from the clip in 3 T. Over the whole region, the distortions caused by the clip were less than 0.3 mm and 1.6 mm under 1.5-T and 3-T MRI, respectively. The geometric accuracy of 1.5-T MRI was better than 3-T MRI and thus better for GKSRS treatment planning. 3-T MRI, however, appears less suitable for use in treatment planning.
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  • PET 画像におけるPSF 補正が定量値に与える影響─ファントム実験と臨床画像からの検討─
    中村 明弘, 谷崎 靖夫, 竹内 美穂, 伊東 繁, 佐野 由高, 佐藤 真由美, 菅野 敏彦, 岡田 裕之, 鳥塚 達郎, 西澤 貞彦
    2014 年 70 巻 6 号 p. 542-548
    発行日: 2014年
    公開日: 2014/06/20
    DOIhttps://doi.org/10.6009/jjrt.2014_JSRT_70.6.542
    ジャーナル フリー
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    While point spread function (PSF)-based positron emission tomography (PET) reconstruction effectively improves the spatial resolution and image quality of PET, it may damage its quantitative properties by producing edge artifacts, or Gibbs artifacts, which appear to cause overestimation of regional radioactivity concentration. In this report, we investigated how edge artifacts produce negative effects on the quantitative properties of PET. Experiments with a National Electrical Manufacturers Association (NEMA) phantom, containing radioactive spheres of a variety of sizes and background filled with cold air or water, or radioactive solutions, showed that profiles modified by edge artifacts were reproducible regardless of background μ values, and the effects of edge artifacts increased with increasing sphere-to-background radioactivity concentration ratio (S/B ratio). Profiles were also affected by edge artifacts in complex fashion in response to variable combinations of sphere sizes and S/B ratios; and central single-peak overestimation up to 50% was occasionally noted in relatively small spheres with high S/B ratios. Effects of edge artifacts were obscured in spheres with low S/B ratios. In patient images with a variety of focal lesions, areas of higher radioactivity accumulation were generally more enhanced by edge artifacts, but the effects were variable depending on the size of and accumulation in the lesion. PET images generated using PSF-based reconstruction are therefore not appropriate for the evaluation of SUV.
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  • 有鉤骨鉤基部撮影における撮影体位の検討
    髙松 俊介, 宮川 誠一郎, 佐藤 久弥, 鈴木 航, 西澤 剛, 中村 雅美, 梅田 宏孝, 崔 昌五, 加藤 京一, 中澤 靖夫, 池田 ...
    2014 年 70 巻 6 号 p. 549-555
    発行日: 2014年
    公開日: 2014/06/20
    DOIhttps://doi.org/10.6009/jjrt.2014_JSRT_70.6.549
    ジャーナル フリー
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    The hamate bone, one of the carpal (wrist) bones, has a large uncinate process protruding from the palm side. In sports such as golf and tennis, the hamate bone can break if is subjected to a high external force, such as from the handle of a racquet or club. At our hospital we take X-ray images of the hamate bone from two directions: an axial image through the carpal tunnel and an image at the base of the hamate hook (conventional method). While the conventional method makes it easy to create images of the base of the hamate hook, the patient may suffer pain during image-taking because the hamate bone is pulled to cause radial flexion. We therefore investigated a method of imaging that would create three-dimensional computed tomography (3DCT) images of the base of the hamate hook in which the patient would only have to only rotate the wrist externally and elevate the fore-arm without any radial flexion. Our results suggest that it is possible to obtain images of the base of the hamate hook as clear as those acquired using the conventional method with the patient in a comfortable and painless position taking images at an external rotation angle of 50.3° and a forearm elevation angle of 20.3°.
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  • 脊椎照合法を用いた体幹部画像誘導放射線治療における総合精度の検討
    中澤 寿人, 内山 幸男, 小森 雅孝, 林 直樹
    2014 年 70 巻 6 号 p. 556-561
    発行日: 2014年
    公開日: 2014/06/20
    DOIhttps://doi.org/10.6009/jjrt.2014_JSRT_70.6.556
    ジャーナル フリー
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    Stereotactic body radiotherapy (SBRT) for lung and liver tumors is always performed under image guidance, a technique used to confirm the accuracy of setup positioning by fusing planning digitally reconstructed radiographs with X-ray, fluoroscopic, or computed tomography (CT) images, using bony structures, tumor shadows, or metallic markers as landmarks. The Japanese SBRT guidelines state that bony spinal structures should be used as the main landmarks for patient setup. In this study, we used the Novalis system as a linear accelerator for SBRT of lung and liver tumors. The current study compared the differences between spine registration and target registration and calculated total spatial accuracy including setup uncertainty derived from our image registration results and the geometric uncertainty of the Novalis system. We were able to evaluate clearly whether overall spatial accuracy is achieved within a setup margin (SM) for planning target volume (PTV) in treatment planning. After being granted approval by the Hospital and University Ethics Committee, we retrospectively analyzed eleven patients with lung tumor and seven patients with liver tumor. The results showed the total spatial accuracy to be within a tolerable range for SM of treatment planning. We therefore regard our method to be suitable for image fusion involving 2-dimensional X-ray images during the treatment planning stage of SBRT for lung and liver tumors.
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資料
特別企画　会員インタビュー～学会に貢献された人々～
教育講座—モンテカルロシミュレーションの放射線技術への利用—
基礎講座—心臓病（特に虚血性心疾患）の診断から治療まで—
基礎講座—画像再構成の基礎と臨床応用—
JIRAトピックス
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